* add elementwise pool2d, prelu, shuffle channel
test=develop

* add scale and refine concat eltwise conveter
test=develop

* refine elementwise converter
test=develop

* refine ut test and enforce error.
test=develop

* modify const cast
test=develop

* fix trt bugs when sharing params, test=develop

* add unittest for cascade_rcnn

* fluid int8 train and trt int8 predict align.
trt int8 predict init
op converter

* 2. align fluid int8 train and trt int8 inference.
enhance quant dequant fuse pass
enhance op converter, trt engine, trt engine op, trt subgraph pass.

* 3. add delete_quant_dequant_pass for trt

test=develop

* 4. add the missing file
test=develop

* 5. i modify the c++ interface, but forget to modify the pybind code
fix the IS_TRT_VERSION_GE bug, and fix elementwise op converter
test=develop

1). add static trt load model
2). fix bug: when device_id is not 0, the trt will have a bug
test=develop

1). add static trt load model
2). fix bug: when device_id is not 0, the trt will have a bug
test=develop

* Initialize the elementwise plugin.

* Implement the basic CUDA kernel of elementwise plugin.
test=develop

test=develop